1. Field of the Invention
The invention relates to a thin film magnetic head having an inductive magnetic transducer for writing and a method of manufacturing the same.
2. Description of the Related Art
Recently, an improvement in performance of a thin film magnetic head has been sought in accordance with an increase in a surface recording density of a hard disk drive. For example, a composite thin film magnetic head, which has a laminated structure comprising a recording head having an inductive magnetic transducer for writing and a reproducing head having a magnetoresistive (hereinafter referred to as MR) element for reading, is widely used as the thin film magnetic head.
For example, the recording head includes a top pole and a bottom pole provided respectively on and under a write gap, a coil for generating a magnetic flux provided between the top pole and the bottom pole, and an insulating layer for insulating the coil from the top pole and the bottom pole. The top pole and the bottom pole have the same uniform width near the write gap near and in a recording-medium-facing surface (an air bearing surface) to be faced with a magnetic recording medium (hereinafter referred to as xe2x80x9ca recording mediumxe2x80x9d), and these portions constitute xe2x80x9ca magnetic pole portion (pole portion)xe2x80x9d for determining a write track width. The pole portion is formed in a certain manner. For example, the top pole having a uniform-width portion constituting a part of the pole portion is formed, and thereafter the write gap and the bottom pole are etched in self-alignment by using the uniform-width portion as a mask.
In the recording head, a current passes through a coil from an external circuit at the time of an information recording operation, and thus a magnetic flux is generated in response to the current. Mainly, the generated magnetic flux flows into the top pole, propagates to a portion having a uniform width constituting a part of the pole portion (hereinafter referred to as xe2x80x9ca uniform-width portionxe2x80x9d), and reaches to a tip portion of the uniform-width portion close to the air bearing surface. A signal magnetic field for recording is generated outside near the write gap by the magnetic flux that reaches to the tip portion, and thus the magnetic recording medium is partly magnetized by the signal magnetic field, so that information is recorded on the magnetic recording medium.
To improve recording characteristics of the performance of the recording head, e.g., characteristics of overwriting information (overwrite characteristics), it is required that a sufficient level of magnetic flux is supplied to the uniform-width portion of the top pole in order to sufficiently generate a signal magnetic field. To increase a recording density, it is required that a width of the pole portion (a pole width) is quite reduced to the submicron order so as to increase a track density on the recording medium. In this case, preferably, the pole width is uniform with high accuracy over the entire area of the pole portion. It is because a side erase phenomenon occurs, when the pole width is partly great, that is, information is written on an adjacent track region as well as a track region on which the information is to be written, so that information written previously on the adjacent track region is overwritten with the newly written information, which is thus erased.
However, for example, when a shape of the top pole is designed so as to necessarily and sufficiently supply magnetic flux to the uniform-width portion for the purpose of improving the overwrite characteristics, the overwrite characteristics improve, whereas the accuracy in forming the uniform-width portion deteriorates and therefore it becomes difficult to reduce the pole width to the submicron order (e.g., 0.5 xcexcm or less). In other words, there has been heretofore a problem that it is difficult to achieve both the improvement of the overwrite characteristics and the reduction of the pole width with high accuracy.
The invention is designed to overcome the foregoing problem. It is an object of the invention to provide a thin film magnetic head and a method of manufacturing the same, which can quite reduce a pole width with high accuracy while improving overwrite characteristics.
According to the invention, there is provided a thin film magnetic head comprising: two magnetic layers magnetically coupled to each other and having two magnetic poles which face each other with a gap layer in between and are arranged to be faced with a recording medium, a thin film coil provided between the two magnetic layers, and an insulating layer for insulating the thin film coil from the two magnetic layers, wherein one of the two magnetic layers includes a laminate constituted of an underlayer and a coating layer, the underlayer being located closer to the gap layer, the coating layer being located away from the gap layer, the coating layer includes a first uniform-width portion and a first wider portion, the first uniform-width portion extending from a recording-medium-facing surface facing the recording medium to a first coupling position away from the recording-medium-facing surface and having a uniform width for determining a write track width on the recording medium, the first wider portion being magnetically coupled to the first uniform-width portion at the first coupling position and having a width greater than that of the uniform width of the first uniform-width portion, and the underlayer includes a second uniform-width portion and a second wider portion, the second uniform-width portion extending from the recording-medium-facing surface to a second coupling position which locates closer to the recording-medium-facing surface than the first coupling position and having a uniform width corresponding to the uniform width of the first uniform-width portion, the second wider portion being magnetically coupled to the second uniform-width portion at the second coupling position and having a width greater than that of the uniform width of the second uniform-width portion.
According to a first aspect of the invention, there is provided a method of manufacturing a thin film magnetic head including: two magnetic layers magnetically coupled to each other and having two magnetic poles which face each other with a gap layer in between and are arranged to be faced with a recording medium, a thin film coil provided between the two magnetic layers, and an insulating layer for insulating the thin film coil from the two magnetic layers, wherein steps of forming one of the two magnetic layers includes: a first step of forming a precursory underlayer so as to coat the insulating layer and a peripheral region around the insulating layer; a second step of forming on the precursory underlayer a coating layer as a part of the one of the two magnetic layers, so that the coating layer includes a first uniform-width portion and a first wider portion, the first uniform-width portion extending from a recording-medium-facing surface facing the recording medium to a first coupling position away from the recording-medium-facing surface and having a uniform width for determining a write track width on the recording medium, the first wider portion being magnetically coupled to the first uniform-width portion at the first coupling position and having a width greater than that of the uniform width of the first uniform-width portion; a third step of selectively forming a patterning mask so as to coat the coating layer and part of the precursory underlayer; and a fourth step of selectively etching the precursory underlayer through the use of the patterning mask, thereby selectively forming an underlayer as another part of the one of the two magnetic layers, so that the underlayer includes a second uniform-width portion and a second wider portion, the second uniform-width portion extending from the recording-medium-facing surface to a second coupling position which locates closer to the recording-medium-facing surface than the first coupling position and having a uniform width corresponding to the uniform width of the first uniform-width portion, the second wider portion being magnetically coupled to the second uniform-width portion at the second coupling position and having a width greater than that of the uniform width of the second uniform-width portion.
According to a second aspect of the invention, there is provided a method of manufacturing a thin film magnetic head including: two magnetic layers magnetically coupled to each other and having two magnetic poles which face each other with a gap layer in between and are arranged to be faced with a recording medium, a thin film coil provided between the two magnetic layers, and an insulating layer for insulating the thin film coil from the two magnetic layers, one of the two magnetic layers including a laminate constituted of an underlayer and a coating layer, the underlayer being located closer to the gap layer, the coating layer being located away from the gap layer, wherein the coating layer is formed so as to include a first uniform-width portion and a first wider portion, the first uniform-width portion extending from a recording-medium-facing surface facing the recording medium to a first coupling position away from the recording-medium-facing surface and having a uniform width for determining a write track width on the recording medium, the first wider portion being magnetically coupled to the first uniform-width portion at the first coupling position and having a width greater than that of the uniform width of the first uniform-width portion, and the underlayer is formed so as to include a second uniform-width portion and a second wider portion, the second uniform-width portion extending from the recording-medium-facing surface to a second coupling position which locates closer to the recording-medium-facing surface than the first coupling position and having a uniform width corresponding to the uniform width of the first uniform-width portion, the second wider portion being magnetically coupled to the second uniform-width portion at the second coupling position and having a width greater than that of the uniform width of the second uniform-width portion.
In the thin film magnetic head of the invention or the method of manufacturing a thin film magnetic head of the second aspect of the invention, one of the two magnetic layers includes the laminate constituted of the underlayer and the coating layer, which are laminated in order from the side of the gap layer. The coating layer includes the first uniform-width portion and the first wider portion magnetically coupled to the first uniform-width portion at the first coupling position, which are provided in order from the side of the recording-medium-facing surface. The underlayer includes the second uniform-width portion and the second wider portion magnetically coupled to the second uniform-width portion at the second coupling position closer to the recording-medium-facing surface than the first coupling position, which correspond to the first uniform-width portion and the first wide portion, respectively. Therefore, a distance between the second coupling position and the recording-medium-facing surface is shorter than a distance between the first coupling position and the recording-medium-facing surface.
In the method of manufacturing a thin film magnetic head of the first aspect of the invention, first of all, in the first step, the precursory underlayer is formed so as to coat the insulating layer and the peripheral region around the insulating layer. Then, in the second step, on the precursory underlayer, the coating layer as a part of the one of the two magnetic layers is formed, so that the coating layer includes a first uniform-width portion and a first wider portion, the first uniform-width portion extending from a recording-medium-facing surface facing the recording medium to a first coupling position away from the recording-medium-facing surface and having a uniform width for determining a write track width on the recording medium, the first wider portion being magnetically coupled to the first uniform-width portion at the first coupling position and having a width greater than that of the uniform width of the first uniform-width portion. Then, in the third step, the patterning mask is selectively formed so as to coat the coating layer and part of the precursory underlayer. Then, in the fourth step, the precursory underlayer is selectively etched through the use of the patterning mask, thereby selectively forming the underlayer as another part of the one of the two magnetic layers, so that the underlayer includes the second uniform-width portion and the second wider portion, the second uniform-width portion extending from the recording-medium-facing surface to the second coupling position which locates closer to the recording-medium-facing surface than the first coupling position and having a uniform width corresponding to the uniform width of the first uniform-width portion, the second wider portion being magnetically coupled to the second uniform-width portion at the second coupling position and having a width greater than that of the uniform width of the second uniform-width portion. Thus, one of the two magnetic layers is formed.
In the thin film magnetic head of the invention or the method of manufacturing a thin film magnetic head of the first aspect of the invention, preferably, a material having a higher saturation magnetic flux density than a saturation magnetic flux density of a material of the coating layer is used as a material of the underlayer. In this case, preferably, a material containing nickel iron, iron nitride or cobalt iron is used as the material of the underlayer, and a material containing nickel iron, nickel cobalt iron or cobalt iron is used as the material of the coating layer.
In the thin film magnetic head of the invention, the coating layer may be formed of a plated film, and the underlayer may be used as an electrode for forming the coating layer by plating.
In the method of manufacturing a thin film magnetic head of the first aspect of the invention, the precursory underlayer may be formed by sputtering, and the coating layer may be formed by plating using the precursory underlayer as an electrode.
In the thin film magnetic head of the invention or the method of manufacturing a thin film magnetic head of the first aspect of the invention, the coating layer may be formed so as to have a thickness between 0.3 xcexcm and 6 xcexcm inclusive, and the underlayer may be formed so as to have a thickness between 0.05 xcexcm and 0.3 xcexcm inclusive.
Other and further objects, features and advantages of the invention will appear more fully from the following description.